4. The biologic width around the dental implant. At the Toronto Conference 1998, the consensus with respect to bone loss around the implant was that bone loss of up to approximately 2 mm during the first year of implant function is acceptable, and at this level the implant is regarded as successful. There have been many reports on studies to ascertain the causes of bone loss around implants and clinical techniques to prevent it. Some reports published in 2005 and 2006 state that the platform switching technique, a technique in which an abutment that is one-size smaller than the implant platform is placed, prevents bone loss around the implant. However, there are only a few reports on the mechanism of action or the extent of bone loss prevention, and as such, it is difficult to say that the effect of PLS has been thoroughly examined. This review article examines the PLS technique and the bone loss preventive effect.